The right answer is A. irradiation.
Food irradiation involves exposing foods to ionizing radiation to reduce the number of microorganisms they contain. Although it is a controversial method of food preservation, it is widely used. This process has been authorized by the Food and Drug Administration and the United States Department of Agriculture. WHO has accepted it for human consumption after extensive scientific research.
It differs from sterilization because it does not necessarily aim to destroy all the germs; Irradiation effectively destroys certain micro-organisms and many bacteria of the Vibrio genus (V. vulfunicus, V. cholerae, V. parahaemolyticus), for example, but strains very resistant to radioactivity or radioresistant are known. Finally, this method can not totally eliminate the risk of viral diseases such as norovirus or hepatitis A virus, but can nevertheless reduce the risk of infection, according to the 2013 publication of the results of work conducted by the University of Delaware.